Rheostat



Patented Aug. 9, 192

UNITED stares PATENT OFFlCE.

JAMES C. SNELL, F OAK PARK, ILLINOIS, ASSIGNOR TOl YREMIER ELECTRIC COM-PANY, OF CHICAGO, ILLINOIS,

`A CORPORATION OF ILLINOIS.

RHEosTAT.

Application filed May 2,

The invention relates to rheostats.

One of the objects of the invention is to provide an improved rheostatwhich is composed mainly of stampinvs, so that it can be produced at alow cost and in large qualitities. Another object of the invention is toprovide an improved construction in which provision is made forpreventing looseness in the shaft or stud for operating the contact armacross the windings. Another object of the invention to provide animproved rheostat which is simple in construc tion and efficient inoperation.

The invention consists in theseveral novel features .hereinafter setforth and more pan ticularly defined by claims at the conclusion hereof.

InV the drawings: Fig. 1 is a front eleva` tion of a device embodyingthe invention. Fig. 2 is an end elevation. Fig. 3 is a vertical section.Fig. 4 is a horizontal section on an enlarged scale. Fig. 5 is a detailOf the resistance element,.the plate on which it is wound and theconductor terminals i around the core plate8 and constitutes theresistance element; a terminal strip adja cent and conforming to one endvof the mar` gin and against oneface of the plate 8, and to which oneterminal of the resistance wire 9 is connected; a plate of insulation11, sub stantially conforming in outline to the plate 8 and extendingover the back of the wind- ,ingsk of the coil 9 and against the endmargins of the. back of plate 8; a terminal strip 12 conformingsubstant-iallyto the end margin of the plate 8 opposite to that on whichthe strip 10 is disposed, fitting against the co1responding marginal`portion of insulating plate 11 and to which the other terminal of theresistance coil 9 is electrically con nected; an insulating plate 18,conforming in outline substantially to the plate 8 and fitting againstthe front of the coil 9, one margin of the plate 8 and against the stripy10; a back plate 14, conforming in outline 'substantially to the coreplate 8 and fitting `1925. ysentii N. 27,399.`

against the back face of insulating plate 11 and terminal strip 12; afront plate 15 also conforming substantially in outline to the coreplate and the back plate 14; 4plates 14 and 15 being formed withindented ribs or beads 83 to stiffen them transversely; an arched orforwardly bowed bearing bracket comprising an integral hub 16,'diagonalarms 17 and perforated lugs 18 which eX- tend tov and lap the corners ofthe front plate 15.l Rivets 19 extend through the corners of the plates15, 18, 8, 11 and 14 and also through the yterminal strips 10 and 12parts in connected and operative relation.

Plates 14, 15 and'strips 10 and 12 are of '7 sheetV metal andinay bereadily and cheapl produced by punclrpress work. Plates 8, 111 and 18arc also formed of sheet insulation, so that they may be readilyproduced by cutting and punching and at a low cost. The bracket is alsoformed of a plate of sheet metal. This construction thus eXem plifiesone in which the core, insulating plates and the supporting or framemembers are all adapted to be produced by punch-press work and to beproperly secured, together by rivets extending through all of saidparts. The hub 18 of the front bracket platehas an inturnecl portion 2Owhich is screw-threaded to receive a correspondingly threaded sleeve 29which forms a bearing for a shaft 21.v This sleeve 29 is adapted t clampthe bracket to supporting panel terial has its hub riveted.I as at 24,to the inner end of shaft 21, and has a backwardly yturned terminalwhich extends through `an arcuate slot 2G in the front plate 15 andinsulating plate 13, and is adapted to Contact with the coils of theresistance element to include more or less of them in thecircuif. Arm 8is bowed forwardly and is provided with arms 27 and 28 extendingoppositelv from the arm to engage the front face of plate 15 toresilientlypress the shaft 21 forwardly. A conoidal disk 30 has itsconstrieted end riveted at 24 to the rea-r end of shaft 21 and itsenlarged end adapted to engage the back face of the hub 18 of the supporting bracket. The oppositely extending spring arms function to pressthe shaft for wardly so the outer margin of the diskwill cause thepressure to be exerted upon the shaft in true axial direction, so thatthe shaft Will be freely operable and Will vnot rattle. This springpressure insures Contact between the contact arm and the core andbetween the arms 27 and 28 and the front plate 13, Which are included inthe circuit.

yThese arms also insure a secondary path for current through arm 23,disk 30 and the supporting bracket. The inner end of sleeve 29 andinturned flange 2O extend into disk 30, so that. the rheostat may besupported from panels 22 of different thickness Without having the frontend of the sleeve project varying distances from the front of the panel.

In operation, the circuit Will be as follows: Terminal strip 10,resistance coil 9, arm 23, arms 27, plate 13, rivets 19 and backplate 14and terminal strip 12, the resistance included in the circuit dependingupon the position of the arm 23 which may be turned toinclude any numberofthe coils in the circuit to vary the resista-nce as desired. `When thearm is at the right-hand side and in engagement with the terminal strip10, the resistance coilwill be short circuited. When arm 23 is inengagement with the insulation at the left-hand margin, the circuitthrough the resistance coil will be open.

The invention exemplifies a rheostat .vhi ch .may be formed essentiallyof stampings of metal and insulating material; also .f1v rhcostat inwhich provision is made for preventing play or looseness in theAoperation of the shaft for rotating the contact arm by means of aresilient contact element and furthermore, the construction results in afloating shaft, which is selfaligning. In these devifes, it isfrequently inconvenient to provide a comparatively long bearing for the.shaft, and by means of the construction described, a short bearingsuffices t0 properly' hold the shaft in use. The device is simple inconstruction and efficient in operation.

The invention is not to be understood as' restricted to the details setforth, since these may be modified within the lscope of the appendedclaims, Without departing from the spirit and scope of the invention.

Having thus described the invention, what I claim as new and'desire tosecure by Let ters Patent, is:

1. In a rheostat, the combination of a substantially flat rectangularcore plate, a re` sistance element vWound around said plate to form arectangular flat faced coil, terminal strips connected to the resistanceelement, a supporting bracket secured to the plate, a shaft carried bysaid bracket, and a- Wip-er carried on the shaft to contact with theresistance element ou a flat face thereof.

In a rheostat, the combination of a sub-- siantia'lly 'fiat rectangularcore plate, a resistance element wound around said plate to form arectangular fiat faced coil, insulating plates against the resistanceelement and cover-plates having margins conforming substantially.1 tothe core plate, a supporting bracket secured to the plates, a shaftcarried bv said bracket, and a Wiper carried on thc shaft to contactwith the resistance element on a flat face tl'icreof.

3. In a rheostat,fthe combination of a substantially flat rectangularcore plate, a resistance element wound around said plate to form arectangular' fiat faced coil, insulating plates against the resistanceelement, and cover plates having margins conforming substantially to thecore plate, an arched supporting bracket secured to the plates, a shaftcarried by said bracket, and a wiper carried on the shaft to contactWiththe resistance element on a flat face thereof.

4. In a rheostat, the combination of a substantially flat rectangularcore plate, a resistance element Wound around said plate, insulatingplates against the resistance elements, and frame-plates having marginsconforming substantially` to the core plate, terminal strips connectedto the element and disposed along opposite margins of the plates, anarched supporting bracket secured to the cover plates, a shaft carriedbysaid bracket, and means on the shaft to contact with the element.

5. In a rheostat, the combination of a coro, Va resistance element Woundaround the core. a supporting bracket for the core, a shaft slidablymounted in the bracket provided with a resilient contact arm for wipingover the element and oppositely arranged resilient arms all acting topress the shaft toward the bracket` and a stop collar on the shaftengaging the bracket under pressure of said arms.

6. In a rheostat.l the combination of a core, a resistance element Woundaround the core, a supporting bracket for the core, a shaftrotatab'leand slidable in the bracket,a shaft operated contact for engaging theresistance element, a cupped disk fixed to the shaft engaging thebracket to limit the movement of the shaftr in the bracket, and athreaded shaft supporting sleeve in the bracket for clamping therheostat to panels of different thickness and extending into the cuppeddisk. i

7. In a rheostat, thecombination ofv a core, a resistance element Woundaround tli'e'core. a supporting bracket for the core, a shaft ro!tatable and slidable in the bracket, a resilient arm having a terminalor engaging the relsistance element, and an oppositely extendingresilient arm on the shaft, and a conoidal disk iXed to the shaft andhaving its outer margin engaging the bracket.

8. In a rheostat, the combination ol a core, a resistance yelement woundaround the core a metallic plate secured to and insulated from the core,a supporting bracket for the plate and core, the bracket being providedwith an inwardly extending screw-threaded flange, a sleeve adapted toextend through a panel from the front thereof and threaded to saidflange to clamp the bracket to a panel and provided with means at its:t'iont end whereby it may be turned, a shaft mounted in the sleeve7 anda contact arm carried upon the end of the shaft bet-Ween the sleeve andthe resistance element, a conoidal disk secured to the shaft and havingits outer margin engaging the bracket, and ay sleeve adapted to extendthrough a panel, provided at its front end with means whereby it nia-ybeturned and having its inner end screwythreaded to the bracket andextending into the conoidal disk.

Signed at Chicago, lllinois, this 20th day of April, 1925. JAMES C.SNELL.

